Display and lighting technology developer Universal Display (Nasdaq: OLED) delivered a first-quarter earnings surprise, with revenue increasing 19% year over year and earnings popping by 35%. Investors may want to pick up a few shares of the organic light-emitting diode, or OLED, expert for three reasons:

1. Sales are lumpy, not slowing down. Universal Display has a long history of unpredictable results on a quarter-by-quarter basis. For example, it’s expanding in China, where quarterly royalties and materials orders can vary wildly from one period to the next.

2. It’s the early days of a massive addressable market. OLED displays started out as an exclusive feature for high-end tablet computers and smartphones, but are now moving down to the larger midrange market. Chief Financial Officer Sid Rosenblatt estimates that about one-third of global smartphone shipments come with Universal Display’s OLED screens nowadays, and he expects to be able to serve the entire smartphone market eventually.

3. Universal Display is expanding its horizons. OLED panels are starting to show up in power-efficient lighting products – in the interior cabin of the new Mercedes EQS electric car, in the taillights of several other car brands and in Nintendo’s upcoming video game consoles.

This company is going places, and over the long run, its stock price should follow suit. (The Motley Fool owns shares of and has recommended Universal Display.)

Ask the Fool

Q: This may be morbid, but I’m wondering: What happens to my credit card debt after I die? – G.H., Tulsa, Oklahoma

A: Ideally, you can pay off your cards soon and enjoy many years free of that debt. But if you do die with credit card debt, here’s what happens: Your estate will be settled either by your executor or by a probate court administrator, depending on how you’ve arranged your affairs.

If your estate has available funds, they’ll be used to pay off creditors such as credit card companies. If you and your spouse had a joint credit card, or someone else co-signed your card, the co-owner will be on the hook to pay it off as well. (In community property states like California or Texas, surviving spouses can be held responsible for credit card debt even if they aren’t joint cardholders.)

If there’s no such person and no funds left with which to pay the debt, it will likely remain unpaid. Authorized users of a card are usually not liable for any debts on it, but they’ll need to stop using the card.

Q: Should I be skeptical of a brokerage offering $0 trading commissions? – L.W., Lancaster, Pennsylvania

A: Not at all. Brokerages make money in multiple ways, not just from commissions. For example, they can invest and earn interest on cash deposits in customer accounts. Some brokerages charge for retirement planning and other advisory services. They earn income from fees, too, such as for paper statements, “account maintenance” or closing an account.

Many brokerages are also paid for “order flow” – collecting payments from other companies for sending them trade orders to execute. So don’t worry about the $0 commissions.

My dumbest investment

My dumbest investment was in Rambus. I was in it for the wrong reasons, and had too large a speculative position. – D.J., online

The Fool responds: You didn’t mention what your wrong reasons were, but we can guess. Rambus’ business model has been to develop technology – especially for faster and better memory chips for electronic devices – and then to license it to other companies. That means Rambus doesn’t have to get bogged down in actual manufacturing; instead, it can just collect a cut of what other companies produce.

Things haven’t always gone well for Rambus, though: Its stock peaked well above $100 per share back in 2000, before the internet bubble burst, and it was recently trading near $19.

One problem for Rambus is that there simply aren’t that many chipmakers – so it’s had a relatively small number of potential customers, leaving it vulnerable if and when it loses one. Rambus has also developed a reputation for taking other chip companies to court for violating its patents. This has not endeared it to other companies, and litigation isn’t cheap; Rambus has posted losses instead of profits in more than half the years in the last decade.

Your position in the stock would have been defensible if you’d done your research and developed confidence in its prospects, but you had a large speculative position. And speculating in stocks is risky, as you learned.